The present invention relates to anti-lock braking systems and in particular to a compact anti-lock braking system hydraulic assembly in which a master cylinder, hydraulic booster, modulating valves, accumulator and associated hydraulic hardware are provided in an integrated package which significantly reduces hydraulic connections and reduces manufacturing cost.
Anti-lock braking systems are now well known. Broadly, these systems incorporate an electronic circuit including a microprocessor based computational circuit connected to the wheels of a motor vehicle via one or more wheel speed sensors. The rotational behavior of the wheels, particularly during braking, is analyzed through the medium of appropriate algorithms to sense an imminent wheel lock or skid condition. When such a condition is sensed, the anti-lock braking system automatically assumes control of the vehicle braking to modulate the application of braking forces to effect maximum vehicle braking and prevent locking of the wheels. In the practical implementation of such systems, a significant number of elements must be incorporated. For example, the system must include a dual circuit master cylinder, means for providing a power assist to the master cylinder such as a hydraulic booster or a vacuum booster, a plurality of high speed solenoid actuated valves, pressure and differential pressure switches, proportioning valves, and the like. Because of the limited space available in contemporary engine compartments and the necessity of minimizing hydraulic line length and connections and the need to provide a system that can be conveniently mounted in a variety of vehicles, it is necessary to provide a compact, low cost, and efficient integrated system incorporating all of the required components. Such integrated systems are, for example, described in SAE Technical Papers Nos. 830483 entitled "The First Compact Four-Wheel Anti-Skid System with Integral Hydraulic Booster", by H. W. Bleckmann, et al, dated Feb. 28-Mar. 4, 1983 and No. 840467 entitled "Pressure Modulation in Separate and Integrated Anti-Skid Systems with Regard to Safety", by W. D. Jonner, et al, dated Feb. 27-Mar. 2, 1984. These prior art integrated systems have, however, continued to be relatively complex and there continues to exist a need for a more compact, efficient, and cost-effective integrated anti-lock braking system assembly.
Broadly, the present invention is an integrated, anti-lock braking system hydraulic assembly. The assembly includes a main body having an elonged cylindrical bore therethrough in which are operatively situated a conventional dual circuit master cylinder and hydraulic booster. A plurality of fluid passages are formed in the body in parallel relationship with the bore in symmetrical arrays. A first plurality of modulating valve receptacles are formed in the body adjacent one end thereof. A plurality of chambers are formed in the body distal the receptacles, and the receptacles and the chambers are provided with fluid passages communicating with predetermined ones of the first fluid passages. A system of modulating valves are received in the receptacles, and differential pressure valves and proportioning valves are disposed in the chambers.
In one embodiment of the invention, the receptacle end of the body is provided with a bracket engaging portion slidably engagable with a bracket, the latter being of variable geometry to accommodate mounting of the assembly to variously configured firewalls. A pressure switch receiving receptacle may further be provided in the receptacle portion of the body.
Means are provided for mounting a fluid accumulator, a fluid pump, pressure relief valve, and a fluid reservoir. The assembly is substantially symmetrical, requires a minimum of external hydraulic connections, and occupies a space equal to or smaller than a conventional vacuum boosted master cylinder assembly.
It is therefore an object of the invention to provide a compact integrated hydraulic assembly for an anti-lock braking system.
It is another object of the invention to provide such an assembly which is substantially symmetrical and occupies the space of a conventional vacuum boosted master cylinder.
Still another object of the invention is to provide such an assembly which provides a major portion of hydraulic connections between the components of an anti-lock braking system within a single body.
Another object of the invention is to provide such an assembly which includes means for mounting same that will accommodate mounting to variously configured firewalls.
Yet another object of the invention is to provide such an assembly which can be manufactured using straightforward manufacturing techniques at a minimum cost and which is adaptable to anti-lock braking systems of various configurations.